Microsoft Lumia 640 Smartphone unable to connect to open wireless network

[cjackson_ncl]

We have a public wireless network infrastructure in our local borough. Users connect to the public SSID which is open, but then authenticate to the network via captive portal.

We have come across a user who is unable to connect to the public SSID, but can connect to SSID published from the same APs which have PSK authentication. I was just wondering if anybody else has come across this before?

[Venkat_FTNT]

Can you please provide additional information ?

Which AP / controller model - SW version? Radio configuration for PSK and Guest SSID . Any load balancing or user limit configuration on guest SSID etc.?

and is the Lumina 640 upgraded to the latest FW?